A metallic glass is often viewed as an amorphous alloy exhibiting a single endothermic reaction in the supercooled liquid region (SCLR, Δ T x = Tx - Tg). Here we discuss the origin and consequences of abnormal behavior of SCLR in various bulk-forming metallic glasses (BMGs). The two-stage-like endothermic reaction in Ni-based, Cu-based, Zr-based, and Mg-based BMGs can originate from the local immiscibility of liquids, which is closely related to chemical heterogeneity in as-cast BMG. These inflections can be attributed to the overlap of the exothermic reaction for the formation and growth of clusters in SCLR. The abnormal behavior of SCLR can be modulated by controlling cooling rate as well as by tailoring alloy composition, with the consequence that the modulated local heterogeneity in these BMGs can lead to enhanced flexibility of the BMGs. This correlation assists in understanding toughening mechanism and in guiding alloy design to alleviate brittleness of BMGs.
Bibliographical noteFunding Information:
This work was supported by the Global Research Laboratory Program of the Korean Ministry of Science. One of the authors (E. S. Park) was supported by a grant from the Fundamental R&D Program for Core Technology of Materials funded by the Ministry of Knowledge Economy, Republic of Korea. The authors are indebted to Professor K. Hono at NIMS, Japan for the 3DAP experiment and Professor Frans Spaepen at Harvard University for thoughtful advice.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)